Optical information reproducing devices, including optical information recording devices, e.g. CD-ROM, DVD-ROM, CD-RW, DVD-RAM, have been widely used as the basic components within the multimedia computer systems. Typical optical reproducing devices can retrieve audio signals, i.e. the signals with audio CD format, signals with MP3 format, or audio signals with other format, recorded on the compact disc. Usually the audio signals retrieved from optical reproduction devices must be processed by audio processing devices, like a sound card, before they are transmitted to the speakers.
With reference to FIG. 1(a) and FIG. 1(b), the method of prior art for a sound processing device to support an optical information reproducing device will be described as follows. As shown in FIG. 1(a), a typical audio processing device 12, i.e. a sound card, includes an audio input port 121 to connect with an optical information reproducing device 11. As is conventional, the audio output port 112 of optical information reproducing device 11 is electrically connected to the audio input port 121 via a bus 13. As shown in FIG. 1(a), the bus 13 includes a connector 14 connecting to the audio output port 112 and a connector 15 connecting to the audio input port 121. While the audio output port 112 is connected to the audio input port 121 via the bus 13, the audio signals recorded on a compact disc are retrieved by the optical information reproducing device 11, output from the audio output port 112 to the audio input port 121 of the audio processing device 12 via the bus 13, processed by the audio processing device 12, and transmitted to the speakers 16. Usually, the bus 13 includes a first signal line 131 (right audio line), a first ground line 132, a second ground line 133, and a second signal line 134 (left audio line) that are used for transmitting audio signals for the left and right speakers respectively to generate stereo audio effect.
For the purpose of easy assembly with other components of a computer system, the audio output port 112 is usually provided on the back panel 111 of the optical information reproducing device 11 as shown in FIG. 1(a). In addition, the audio processing device 12, which is generally in form of an interface card, usually provides one audio input port 121. Apparently, under such arrangement, the audio processing device can only support one optical information reproducing device. While more then one optical information reproducing devices are present in the computer system and the audio processing device is expected to support all optical information reproducing devices existing, changes on hardware connection are unavoidable.
Also shown in FIG. 1 (a) is that a typical audio processing device 12 not only includes an audio input port 121 but also includes an audio input jack 122. As shown in FIG. 1(b), another optical information reproducing device 17 is able to utilize an audio signal line 18, usually an earphone line, to connect an audio input jack 172 on the front panel 171 thereof to the audio input jack 122 of the audio processing device 12. Therefore, the audio processing device 12 can support two optical information reproducing devices 11 and 17. However, this method requires a longer audio signal line and the audio signal line is located outside the computer system. Since the audio input jack 122 is located on the back side of the system while the audio output jack 172 is located on the front side of the system, inconvenience during connections of various connectors exists. Besides, the method can only support at most two optical information reproducing devices to share one audio processing device. Therefore, it is still not convenient enough for the users.
Nowadays, a computer system is often equipped with more than one optical information reproducing devices and one audio processing device. The purpose of the invention is to provide a method and an apparatus to meet the need recited above while without changing the hardware connection design of the optical information reproducing devices and the audio processing devices. By the method and the apparatus provided, at least two optical information reproducing devices can be connected to an audio processing device and share the same audio processing device. What comes with the invention is that users can selectively play an audio CD, a MP3 format CD etc. in each optical information reproducing device as they wish. Therefore, the invention provides the users with great convenience.